1. Technical Field
Various embodiments generally relate to a semiconductor memory device and more particularly, to a nonvolatile memory device.
2. Related Art
Semiconductor memory devices may be realized using semiconductor materials such as silicon (Si), germanium (Ge), gallium arsenide (GaAs) and indium phosphide (InP). Semiconductor memory devices are generally classified into volatile and nonvolatile memory devices.
A volatile memory device does not retain stored data when its power supply is turned off. Examples of volatile memory devices include SRAM (static RAM), DRAM (dynamic RAM) and SDRAM (synchronous DRAM) devices. A nonvolatile memory device retains stored data even when its power supply is turned off. Examples of nonvolatile memory devices include ROM (read only memory), PROM (programmable ROM), EPROM (erasable programmable ROM), EEPROM (electrically erasable programmable ROM), flash memory, PRAM (phase change RAM), MRAM (magnetoresistive RAM), RRAM (resistive RAM), and FRAM (ferroelectric RAM) devices.